1. Field of the Invention
This invention relates to a coaxial connector switch, and more particularly to such a switch in which a cover plate is attached to a switch portion of a coaxial connector so as to prevent the increase of a contact resistance of the switch portion of the coaxial connector due to the intrusion of flux and also to prevent the intrusion of dust.
2. Description of the Related Art
There has been extensively used a coaxial connector switch which is connected to an antenna on an automobile via a coaxial adapter, connected to the automobile antenna, so that the automobile antenna can be used as an antenna of a portable cellular telephone.
FIG. 3 is a bottom view showing the construction of a conventional coaxial connector switch. FIG. 4 is a cross-sectional view taken along the line 4--4 of FIG. 3, showing the construction of the conventional coaxial connector switch.
The construction of the conventional coaxial connector switch will now be described with reference to FIGS. 3 and 4. In FIG. 4, a dielectric member 21, in which a center pin 23 is inserted, is fitted on a funnel-shaped outer conductor 24. The center pin 23 is held in contact with a first contact leg 26, including a resilient contact arm 25 having a contact projection, and the center pin 23 is urged upward by a resilient force of the first contact leg 26.
The first contact leg 26 is contacted at its contact projection with a second contact leg 27 so that a signal can be fed from the first contact leg 26 to the second contact leg 27. When the center pin 23 is pushed by a coaxial adapter 40, the signal can be fed from the first contact leg 26 to the center pin 23. This will be described later.
Although not shown in FIG. 4, a terminal 28 of the first contact leg 26 and a terminal 29 of the second contact leg 27 are mounted (surface mounted) by reflow soldering on a conductor on a surface of a printed circuit board. Also, first and second terminals 31 and 32 (shown in FIG. 3), formed on the outer conductor 24, are mounted (surface mounted) on the conductor of the printed circuit board by reflow soldering.
Next, the operation of the conventional axial connector switch will be described with reference to FIG. 5. In FIG. 5, the coaxial adapter 40 is pushed into the coaxial connector switch in a direction of an arrow, a central conductor 41 abuts against the center pin 21 to push the same downward. As a result, the center pin 21 is moved downward against the bias of the first contact leg 26, so that the flow of the signal from the first contact leg 26 to the second contact leg 27 is interrupted.
At this time, an outer conductor 42 surrounding dielectric portion 43 of the coaxial adapter 40 is brought into contact with the outer conductor 24 of the coaxial connector switch, so that signals from the terminals 31 and 32, formed on the outer conductor 24 of the coaxial connector switch, are connected to the outer conductor 42 of the coaxial adapter 40, and also the signal from the first contact leg 26 of the coaxial connector.
As a result, the flow of the signal from the first contact leg 26 is switched to the central conductor 41 of the coaxial adapter 40, and therefore the automobile antenna can be used as an antenna of the portable cellular telephone.
In the above conventional coaxial connector switch, however, a cover plate is not provided at the switch portion of the coaxial connector; therefore, the rising of flux due to surface tension during the surface-mounting operation by the reflow soldering can not be prevented, so that the contact resistance is increased by the flux, and in the worst case, there has been encountered a disadvantage that the switch portion has failed to function as a switch.